Harvistor LLC, Copyright 2015 All Rights Reserved. R. Reive
Let’s start with a simple definition…
Electrical Load Management = Expensive Electrical Braking + Wind Assisted Mechanical Braking. (Electro-mechanical braking)
Electrical Load Management = Low Cost Electrical Braking + Starwnd5 Optiflow Assisted Aerodynamic Braking
And a little know fact!
“Burnout Protection is the Hidden Performance Cost of Small & Micro Wind Turbines! “
And a current buyer behavior “Faux Pax”:
Use of Cost/W and Power Efficiency Evaluation only to make a small wind turbine purchase.
I will cut to the chase here, and save you the read below with a bit of valuable advice.
“When buying small/micro wind powered generation Use LCOE versus Cost/W .
The small/micro wind turbine parameters of Cost/W and Power Efficiency (Cp- Coefficient of Power) are not enough to make an informed decision to buy a 20 year useful life asset.
For those who are interested in the details, read on,
LCOE: What is it in the context of “Burnout Protection”?
The LCOE “Levelized Cost of Energy” in the “Burnout Protection” context, means summing up all the material, equipment and labour costs required to a create an electro-mechanical braking design that is robust enough in high wind speeds to keep a small wind turbine from spinning too fast and burning out the generator set.
In fact all commercial market leading small and micro wind turbine vendors in the Top five for sales of wind turbines of the day never mention Burnout Protection or the related LCOE for this mandatory feature, because if they did, such disclosure to the buyer would show how their legacy small and micro HAWT solutions to Burnout Protection are really a “band-aid” to fix poor aerodynamic designs adopted from old larger HAWT designs first created in 1935 to 1978 using aircraft airfoils and why the market segment has not advanced since until the advent of Starwind5.
Today’s Small Wind Burnout Protection Band-Aids: Electrical Load Management via expensive inverters/converters combined with electrical and/or mechanical brakes and/or routine Power Dumps to Heat Sinks.
To help explain the above statement further it’s useful to understand at a high level the following, A Short Electrical Load Management Story: To avoid generator set burn out (build in generator set “Burnout Protection”) it’s a mandatory safety feature for a small wind vendor to intelligently, and consistently manage the electrical load placed on the stator coils of the generator so as not to melt the insulating coating on the copper, which should this melt happen will lead to a short between wires and an electrical fire and destruction or “Burn out” of the generator, the most expensive part of the small wind turbine. Today, By default , vendors employ the battery and/or grid charge controller to perform the electrical load management role enabling “Burnout Protection”, doing so by controlling the resistance levels of the flow of electricity received from the small wind turbine generator so as to feed the public grid circuit with the right voltage as well as the correct sine wave form. The controller also acts to connect and disconnect safely based on control signals received from the public grid, and as well in the battery charging role makes software embedded microprocessor controlled decisions based on current battery levels of what to do with the flow, possibly even splitting the flow received to charge batteries, power the grid, heat a water heater element and even dump to a power sink. All good. A byproduct of this type of electrical flow control is also to be able to intelligently (a micro processor and software is used) store electricity for a short period in capacitors, slow the same flow while dumping heat through resistors (good for unexpected peaks), and convert electricity flow levels via transformers, so effectively slow the flow, which translates into a form of electrically induced mechanical braking, slowing the rate of electron flows which means magnets attached to the spinning rotor of the floating shaft cannot pass as fast by and drive electrons through the statically mounted coils on the stator to the charge controller , where the latter is attached to the fixed shaft. In the worst case when the electrical flow gets really peaky, a breaker or fuse is used to safely re-direct the flow to the ground cable.
Ok armed with the above information, it is easy to see how these functions can also be employed to slow electricity flow and effectively brake the rotational speed of a small wind turbine, provided the resistors, transformers, capacitors and micro-processors reliably act in concert and are sized properly to do this concerted effort over and over again for 20 years. Today most if not all successful HAWT and VAWT Vertical Axis Wind turbine designs employ electrical load management into their own inverters/converters as part of small wind turbine braking to deliver what is effectively called “Burnout Protection”, even though this feature is not mentioned in most product brochures. In VAWT documentation the feature is often called “Overspeed Protection”. Hybrid wind/solar solutions use a single central controller treating the wind controller as a slave charge controller only for programming purposes over a separate control connection, where wind is always treated as the “prime mover” first priority.
LCOE: The short and long stroke story of Blackout Protection Compomising Power Performance
Today, the reality is the legacy crop of propeller based HAWT “Horizontal Axis Wind Turbine” designs purchased from market leaders only get close to their claimed Cp “Coefficient of Power” Claims, the standard measure of Power Performance for small wind turbines, doing so within a very narrow range of wind speed operation of 10-12 m/s metres per second, making such micro or small wind HAWTs very “peaky”. In effect HAWTS are like drag racing cars, HAWTS are “short stroke” systems which accelerate quickly to get to peak when they get a chance ( HAWTS have an average start but are great at trapping gusts as the blades create tremendous lift fast). However like a drag race car rocketing down the strip, small HAWTS are also great at creating large tower dynamic horizontal loads, which in order to avoid such loads (ie slow down the drag race car with a big parachute safely) these small HAWTS not only require lots of good fuel (straight wind found at taller mount heights), they also require more tower and foundation to support the loads created while braking (Furling out of the wind) to avoid generators burn out, at which point the HAWT blades are designed to furl out of the wind (Bergey) with the assistance of a broad angled tail vane or a set of flexible/hinged blades (Xeres/Skystream, LionHead) that bend or lean back away from the wind.
- HAWTS need straight wind which means use of expensive towers and foundations
To keep Cost/Watt low , small HAWT vendors low cost generators have furling and electrical brake limited rpm to ensure cooling flows of 10 cubic feet a minute are maintained to avoid melting of he low cost coil wire insulator material and the subsequent burnout of the low cost coils. Also the Aeordyanmic efficiency of the Rotor blades are tuned to furl out at 13 m/s not only to protect from burnout , but to also protect the blades from horizontal load damage, thus forging 3-6% of the hi wind occurrence found in the 14-24 m/s useful range of the wind flow which yields at least 12-15% of the total AEP at a good wind site with a normal Weibull means of 7 m/s with a normal/average distribution of occurrence “Bell Curve”.
Ok, now it is clear to see that to get a small HAWT to work one needs clear access to straight wind, which requires more tower material, and a larger foundation. Why more material? because of the horizontal loads generated during braking demand it for safety which is regulated in ANSI and IEEE specifications worldwide. Why? To make sure the tower at the higher height can handle the +13 m/s horizontal loads while the wind turbine is braking thereby providing Burnout Protection . Burnout Protection , that hidden cost found in the material height and cost of the turbine tower and foundation which is almost the same price as the HAWT turbine on its own. The size and cost of the concrete foundation or roof top mount system is roughly 50% of the tower or turbine cost. More importantly electrical braking trumpeted as a feature is also hidden in the cost of the inverter/converter used to manage electrical load, which together with furling is also used to effectively control the rpm of the wind turbine, and cut off the rpm at specific speed to avoid generator set burnout. More expensive electronics together with larger resistors, capacitors and transformers mean the inverter costs are higher to facilitate electrical braking assistance for fixed blade HAWTS. Such electrical load management requires larger capacitors, resistors and transformers, as well as more expensive micro-processors (also prone to EMP attacks, but that is another story) to deliver such load management and by default electrically inducing rpm braking of the wind turbine at +13 m/s wind speeds.
HAWTs and early 13 m/s Tail or Blade Furl Activated Burnout Protection = 15% Lost Annual energy Production
- HAWTS: Peaky Cp Power Curves do not convert 3-6% of usable hi speed wind occurrences into 15% useful power.
But the “experts” say HAWTS are inherently cheaper to build than VAWTs? NOT really.. Here is why:
- HAWTS: Early high speed regulation means use of 15-25% cheaper inverter/converters, integrated or external
- HAWTS: The need for straight wind at greater heights to function at rated output combined with the horizontal physical loads induced on the tower and foundation by electro-mechanical braking to deliver Burnout Protection ensure half the installed cost of a small HAWT is for tower and foundation or rooftop mount systems ballast.
Hopefully the cost of Blackout Protection in HAWTS and how it reduces the Power Performance measured by AEP Annual Energy Production by 15% is now simpler for the buyer to understand. Today’s market leading small and micro HAWTS simply cannot convert the 13+ m/s higher speeds which occur 3-6% of the time to capture the effectively lost 12-15% AEP because HAWTS also use cheaper generator sets with narrower rpm ranges and smaller magnets and less copper which do not support the higher rpm. If HAWTS did support the higher +13 m/s speeds the generators would require new aerodynamics with even larger lift capabilities with wider ranges to effectively rotate larger magnet and larger coil generators with more resistance, which increase specific turbine capital costs, ie the retail sticker price, and the turbine costs of manufacture, which because of competitive price/performance pressure (Starwind5) erode margins.
Once thing for sure is the margins of HAWTS today for small wind vendors are potentially quite good selling Cost/W and Cp Coefficient of Power as the only way to buy small wind.
Cost/W of Small and Micro Wind Turbines: A Deceptively simple and erroneous way to buy small wind solutions
The real experts in small wind are right saying current small and micro vendors have not done anything to improve power performance, but have figured out how to build their devices cheaply using offshore labor and material costs to improve Cost/Watt of their systems, the margins and returns to their shareholders. Here are a few tips in avoiding this dual Cost/W and Cp Coefficient of Performance buyers trap when evaluating small wind vendors and their solutions:
Step 1 Get the most “AEP” Annual Energy Production (the true measure of wind turbine performance) from your micro and small wind turbine investment. To do this it requires the proper siting of your small wind turbine at the right height , avoiding really turbulent air masses or wind shadows caused by adjacent tree canopies and man made structures deflecting or slowing wind flow before it reaches your turbine. You need to position the small wind turbine in wind flows it is designed to easily convert the wind kinetic energy into rotational energy and electricity. HAWTS need straight wind and tall expensive towers amounting to 50% of the total solution acquisition cost, and have aerial maintenance costs which are 2X to 4X higher than ground serviced tilt tower systems. Starwind5 uses 35% lower and 50% cheaper tower and foundation vs. all small HAWTs because Burnout Protection is completely aerodynamic using 10-15% more rotor blade and shaft material, so even though the Cost/W of the Starwind5 is 10-15% higher, because no electro-mechanical braking is required, Starwind5 is still 35% cheaper as a complete installed solution vs. any leading HAWT solution of the same NP Name Plate capacity while producing 35% more AEP at the 35% lower height.
Step 2: Once the proper siting is secured for your new clean energy generation investment, given the height restrictions which might apply in urban and sub urban and industrial par locations enforced by city bylaws, it’s always a good idea to compare performance in in these low mount wind conditions, to select the best turbine for such sites, and this is where we know Starwind5 will always rise to the top as the best micro and small wind turbine, because Starwind5 is designed for low mount wind.
Step 3: To protect their investment smart owners of small or micro wind turbine powered generation facilities will always compare the total LCOE Levelized Cost of Energy over a 20 year investment period. LCOE always includes “O&M” Operations and Maintenance Costs over the 20 year useful life of the system. As a smart investor in micro generation, be it off or on grid, savvy buyers will always compare LCOE between different competitive offerings as part of the overall acquisition the “CapEx” Capital Expenditure Cost, the cost of installation as well as the decommissioning and disposal costs to make sure their project is bankable. Ultimately selling the small wind powered generation facility to the bank who is loaning 60-80% of the money to make it happen is the ultimate test. Such loans might also includes an up front analysis of the LCOE for accompanying solar panels, batteries and a small “last resort” backup diesel, natural gas or propane generator. Increasingly, bankers are using LCOE more and more to protect their loans, so users are wise to do same for their own investment im order to get financing.
LCOE is Hot, Cost/W is not… A Summary…
Starwind5 delivers Best in Class Burnout Protection together with Best in Class Power Performance for the best LCOE in small wind.
Where some buyers of small and micro wind erroneously get hung up on is “JUST” the price of the turbine on its own,really Cost/W of the turbine is only 25% of the LCOE equation. Fully 25% is also related to tower/foundation costs, and another 50% is O&M Operations and Maintenance costs is the other 50%. Starwind5 wins every time when measured against the competition using LCOE . Starwind5 is designed for Low Mount Wind with tower and foundation costs which are truly 50% less than leading small/micro HAWTS because of Starwind5’s 35% lower heights. At the lower heights Starwind5 can employ semi turbulent wind to generate 25-35% or more AEP Annual Energy Production than competitive HAWTS mounted 50% higher,, due largely to Starwind5’s unique Optiflow tm Assisted Aerodynamic Braking at wind speeds starting at 18 m/s and limiting top rpm in +24 m/s wind speeds, a feat no other small/micro HAWT or VAWT wind turbine vendor can deliver. At Starwind5 truly LCOE is our mantra because Cost/W is truly only 25% of the game, a game only played by our competitors.
Stay tuned for our next blog to learn more about Starwind5 Optiflow Assisted Aerodynamic Braking delivers Best in Class LCOE for small wind.